White House chief strategist Steve Bannon is one of the most controversial figures in President Donald Trump’s administration. And in a new bestselling book — Devil’s Bargain: Steve Bannon, Donald Trump, and the Storming of the Presidency — Joshua Green takes readers inside the mysterious, up-and-down relationship between the president and his populist guru.

President Trump’s decision to withdraw the United States from the Paris climate accord is the latest example of his raw political instincts pulling him away from the center, in spite of a chorus of moderates in the business community and in the administration urging him to stick with the agreement.